U.S. patent application number 16/882936 was filed with the patent office on 2021-01-28 for structural rectal atlas deformation features for characterizing intra-wall and peri-wall chemoradiation response on magnetic resonance imaging (mri).
The applicant listed for this patent is Case Western Reserve University. Invention is credited to Jacob Antunes, Anant Madabhushi, Pallavi Tiwari, Satish E. Viswanath, Zhouping Wei.
Application Number | 20210027468 16/882936 |
Document ID | / |
Family ID | 1000005065166 |
Filed Date | 2021-01-28 |
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United States Patent
Application |
20210027468 |
Kind Code |
A1 |
Madabhushi; Anant ; et
al. |
January 28, 2021 |
STRUCTURAL RECTAL ATLAS DEFORMATION FEATURES FOR CHARACTERIZING
INTRA-WALL AND PERI-WALL CHEMORADIATION RESPONSE ON MAGNETIC
RESONANCE IMAGING (MRI)
Abstract
Embodiments discussed herein facilitate determination of
responsiveness to chemoradiation treatment in rectal cancer
patients based on structural deformation features obtained from a
pre- or post-treatment medical imaging. One example embodiment can
perform operations comprising: accessing an image volume of a
rectum comprising a rectal tumor; generating a forward mapping
based on non-rigidly registering a healthy rectal atlas to the
image volume; inverting the forward mapping to generate an inverse
mapping from the image volume to the healthy rectal atlas;
determining, based on the inverse mapping, an associated
deformation magnitude for each voxel of a plurality of voxels
associated with the rectum; computing one or more structural
deformation features based on the associated deformation magnitudes
for the plurality of voxels; and predicting via a classifier
whether or not the rectal tumor will respond to the chemoradiation
treatment based at least in part on the one or more structural
deformation features.
Inventors: |
Madabhushi; Anant; (Shaker
Heights, OH) ; Antunes; Jacob; (Cincinnati, OH)
; Wei; Zhouping; (Cleveland, OH) ; Tiwari;
Pallavi; (Wexford, PA) ; Viswanath; Satish E.;
(Pepper Pike, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Case Western Reserve University |
Cleveland |
OH |
US |
|
|
Family ID: |
1000005065166 |
Appl. No.: |
16/882936 |
Filed: |
May 26, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62879044 |
Jul 26, 2019 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G06T 7/337 20170101;
G06T 2207/10088 20130101; G06K 9/6234 20130101; G06K 9/6267
20130101; G06T 7/40 20130101; G06T 7/0014 20130101; G06T 2207/20081
20130101; G06T 2207/30096 20130101; G06K 9/6256 20130101 |
International
Class: |
G06T 7/00 20060101
G06T007/00; G06T 7/33 20060101 G06T007/33; G06T 7/40 20060101
G06T007/40; G06K 9/62 20060101 G06K009/62 |
Goverment Interests
FEDERAL FUNDING NOTICE
[0002] This invention was made with government support under the
grant(s) CA199374, CA202752, CA208236, CA216579, CA2205811,
CA216935, RR12463, EY022947, DK09794, and EB00750912 awarded by the
National Institutes of Health; the grant(s) W81XWH-15-1-0558,
W81XWH-16-10329, W81XWH-18-0404, and W81XWH-18-1-0440 awarded by
the Department of Defense; and the grant(s) IBX004121A awarded by
the United States Department of Veterans Affairs. The government
has certain rights in the invention.
Claims
1. A non-transitory computer-readable medium storing
computer-executable instructions that, when executed, cause a
processor to perform operations, comprising: accessing an image
volume of a rectum comprising a rectal tumor, wherein the image
volume was obtained prior to a chemoradiation treatment of the
rectal tumor; generating a forward mapping based on non-rigidly
registering a healthy rectal atlas to the image volume; inverting
the forward mapping to generate an inverse mapping from the image
volume to the healthy rectal atlas; determining, based on the
inverse mapping, an associated deformation magnitude for each voxel
of a plurality of voxels associated with the rectum; computing one
or more structural deformation features based on the associated
deformation magnitudes for the plurality of voxels; and predicting
via a classifier whether or not the rectal tumor will respond to
the chemoradiation treatment based at least in part on the one or
more structural deformation features.
2. The non-transitory computer-readable medium of claim 1, wherein
the image volume is a Magnetic Resonance Imaging (MRI) image
volume.
3. The non-transitory computer-readable medium of claim 1, wherein
the classifier is one of a Linear Discriminant Analysis (LDA)
classifier, a Quadratic Discriminant Analysis (QDA) classifier, a
Support Vector Machine (SVM) classifier, or a Random Forest (RF)
classifier.
4. The non-transitory computer-readable medium of claim 1, wherein
the one or more structural deformation features comprise one or
more intra-wall deformation features associated with a wall of the
rectum.
5. The non-transitory computer-readable medium of claim 4, wherein
the operations further comprise computing one or more peri-wall
texture features associated with a peri-wall region near a wall of
the rectum, wherein the predicting via the classifier is based at
least in part on the one or more peri-wall texture features.
6. The non-transitory computer-readable medium of claim 1, wherein
the one or more structural deformation features comprise one or
more peri-wall deformation features associated with a peri-wall
region near a wall of the rectum.
7. The non-transitory computer-readable medium of claim 6, wherein
the operations further comprise computing one or more intra-wall
texture features associated with a wall of the rectum, wherein the
predicting via the classifier is based at least in part on the one
or more intra-wall texture features.
8. The non-transitory computer-readable medium of claim 1, wherein
the one or more structural deformation features comprise one or
more of the following computed for at least a subset of the
plurality of voxels: a mean of the deformation magnitude, a median
of the deformation magnitude, a standard deviation of the
deformation magnitude, a skewness of the deformation magnitude, or
a kurtosis of the deformation magnitude.
9. The non-transitory computer-readable medium of claim 1, wherein
the operations further comprise computing one or more texture
features based on the plurality of voxels, wherein the predicting
via the classifier is based at least in part on the one or more
texture features.
10. The non-transitory computer-readable medium of claim 9, wherein
the one or more texture features comprise one or more of at least
one intra-wall texture feature associated with a wall of the rectum
or at least one peri-wall texture feature associated with a
peri-wall region near the wall of the rectum.
11. A non-transitory computer-readable medium storing
computer-executable instructions that, when executed, cause a
processor to perform operations, comprising: accessing an image
volume of a rectum comprising a rectal tumor, wherein the image
volume was obtained after a chemoradiation treatment of the rectal
tumor; generating a forward mapping based on non-rigidly
registering a healthy rectal atlas to the image volume; inverting
the forward mapping to generate an inverse mapping from the image
volume to the healthy rectal atlas; determining, based on the
inverse mapping, an associated deformation magnitude for each voxel
of a plurality of voxels associated with the rectum; computing one
or more structural deformation features based on the associated
deformation magnitudes for the plurality of voxels; and
determining, via a classifier, whether or not the rectal tumor is
responsive to the chemoradiation treatment based at least in part
on the one or more structural deformation features.
12. The non-transitory computer-readable medium of claim 11,
wherein the image volume is a Magnetic Resonance Imaging (MRI)
image volume.
13. The non-transitory computer-readable medium of claim 11,
wherein the classifier is one of a Linear Discriminant Analysis
(LDA) classifier, a Quadratic Discriminant Analysis (QDA)
classifier, a Support Vector Machine (SVM) classifier, or a Random
Forest (RF) classifier.
14. The non-transitory computer-readable medium of claim 11,
wherein the one or more structural deformation features comprise
one or more intra-wall deformation features associated with a wall
of the rectum.
15. The non-transitory computer-readable medium of claim 14,
wherein the operations further comprise computing one or more
peri-wall texture features associated with a peri-wall region near
a wall of the rectum, wherein the predicting via the classifier is
based at least in part on the one or more peri-wall texture
features.
16. The non-transitory computer-readable medium of claim 11,
wherein the one or more structural deformation features comprise
one or more peri-wall deformation features associated with a
peri-wall region near a wall of the rectum.
17. The non-transitory computer-readable medium of claim 16,
wherein the operations further comprise computing one or more
intra-wall texture features associated with a wall of the rectum,
wherein the predicting via the classifier is based at least in part
on the one or more intra-wall texture features.
18. The non-transitory computer-readable medium of claim 11,
wherein the one or more structural deformation features comprise
one or more of the following computed for at least a subset of the
plurality of voxels: a mean of the deformation magnitude, a median
of the deformation magnitude, a standard deviation of the
deformation magnitude, a skewness of the deformation magnitude, or
a kurtosis of the deformation magnitude.
19. The non-transitory computer-readable medium of claim 11,
wherein the operations further comprise computing one or more
texture features based on the plurality of voxels, wherein the
predicting via the classifier is based at least in part on the one
or more texture features.
20. The non-transitory computer-readable medium of claim 19,
wherein the one or more texture features comprise one or more of at
least one intra-wall texture feature associated with a wall of the
rectum or at least one peri-wall texture feature associated with a
peri-wall region near the wall of the rectum.
21. A non-transitory computer-readable medium storing
computer-executable instructions that, when executed, cause a
processor to perform operations, comprising: accessing a plurality
of training image volumes, wherein each image volume of the
plurality of training image volumes comprises an associated rectum
comprising an associated rectal tumor of that image volume, and
wherein each image volume of the plurality of training image
volumes has an associated known response to a chemoradiation
treatment; for each image volume of the plurality of training image
volumes: generating an associated forward mapping for that image
volume based on non-rigidly registering a healthy rectal atlas to
that image volume; invert the associated forward mapping to
generate an associated inverse mapping for that image volume from
that image volume to the healthy rectal atlas; determining, based
on the associated inverse mapping for that image volume, an
associated deformation magnitude for each voxel of a plurality of
voxels associated with the associated rectum of that image volume;
and computing, based on the associated deformation magnitudes for
the plurality of voxels associated with the associated rectum of
that image volume, an associated value for that image volume for
each structural deformation feature of a plurality of structural
deformation features; determining one or more best features for
characterizing response to the chemoradiation treatment from among
a set of features comprising the plurality of structural
deformation features and a plurality of texture features, wherein
the one or more best features are determined based at least on: the
associated known responses for the plurality of training image
volumes and the associated values for the plurality of training
image volumes for the plurality of structural deformation features;
and constructing a classifier configured to classify an additional
image volume comprising an associated rectum with an associated
rectal tumor as responsive or non-responsive to the chemoradiation
treatment based at least on the one or more best features.
22. The non-transitory computer-readable medium of claim 21,
wherein the operations further comprise computing, based on the
plurality of voxels associated with the associated rectum of that
image volume, an associated value for that image volume for each
texture feature of the plurality of texture features, and wherein
the one or more best features are determined based at least on the
associated values for the plurality of training image volumes for
the plurality of texture features.
23. The non-transitory computer-readable medium of claim 22,
wherein the plurality of texture features comprise one or more of
at least one intra-wall texture feature computed for that image
volume from an associated wall of the associated rectum of that
image volume or at least one peri-wall texture feature computed for
that image volume from an associated peri-wall region near the
associated wall of the rectum of the associated rectum of that
image volume.
24. The non-transitory computer-readable medium of claim 21,
wherein the operations further comprise: accessing a plurality of
healthy image volumes, wherein each image volume of the plurality
of healthy image volumes comprises an associated healthy rectum of
that image volume, and wherein an associated rectal wall of the
associated healthy rectum of that image volume has been annotated;
and generating a healthy rectal wall atlas based on the associated
rectal wall of the associated healthy rectum of each image volume
of the plurality of healthy image volumes.
25. The non-transitory computer-readable medium of claim 21,
wherein the plurality of training image volumes is a plurality of
Magnetic Resonance Imaging (MRI) image volumes.
26. The non-transitory computer-readable medium of claim 21,
wherein the classifier is one of a Linear Discriminant Analysis
(LDA) classifier, a Quadratic Discriminant Analysis (QDA)
classifier, a Support Vector Machine (SVM) classifier, or a Random
Forest (RF) classifier.
27. The non-transitory computer-readable medium of claim 21,
wherein the plurality of structural deformation features comprise
one or more intra-wall deformation features computed for that image
volume from an associated wall of the associated rectum of that
image volume.
28. The non-transitory computer-readable medium of claim 21,
wherein the plurality of structural deformation features comprise
one or more peri-wall deformation features computed for that image
volume from an associated peri-wall region near an associated wall
of the associated rectum of that image volume.
29. The non-transitory computer-readable medium of claim 21,
wherein the plurality of structural deformation features comprise
one or more of the following computed for at least a subset of the
plurality of voxels: a mean of the deformation magnitude, a median
of the deformation magnitude, a standard deviation of the
deformation magnitude, a skewness of the deformation magnitude, or
a kurtosis of the deformation magnitude.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Patent Application No. 62/879,044 filed Jul. 26, 2019, entitled
"STRUCTURAL RECTAL ATLAS DEFORMATION (STRAD) FEATURES FOR
CHARACTERIZING INTRA- AND PERI-WALL CHEMORADIATION RESPONSE ON
MAGNETIC RESONANCE IMAGING (MRI)", the contents of which are herein
incorporated by reference in their entirety.
BACKGROUND
[0003] The advent of radiomics has demonstrated great success for
predicting and evaluating treatment response via imaging in
different cancers. Radiomic approaches have typically extracted
morphologic texture or shape descriptors of the tumor region, which
have been related to underlying pathologic or molecular
heterogeneity that drive therapy response. As an example,
prediction of response to chemoradiation in rectal cancers via pre-
or post-treatment MRI has been limited to using morphologic
radiomic descriptors for image appearance alone. Unlike deep
learning approaches (which are data-driven solutions to lesion
segmentation, localization, or detection), radiomics also leverages
"handcrafted" descriptors to quantify specific imaging
characteristics both within and around the tumor. For instance, new
classes of features that quantify tissue deformations or surface
distensions on imaging have been linked to aggressive tumor growth
as well as tumor recurrence, based on available reference atlas
representations in solid organs such as the brain or the
prostate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] The accompanying drawings, which are incorporated in and
constitute a part of the specification, illustrate various example
operations, apparatus, methods, and other example embodiments of
various aspects discussed herein. It will be appreciated that the
illustrated element boundaries (e.g., boxes, groups of boxes, or
other shapes) in the figures represent one example of the
boundaries. One of ordinary skill in the art will appreciate that,
in some examples, one element can be designed as multiple elements
or that multiple elements can be designed as one element. In some
examples, an element shown as an internal component of another
element may be implemented as an external component and vice versa.
Furthermore, elements may not be drawn to scale.
[0005] FIG. 1 illustrates a flow diagram of an example method/set
of operations that can be performed by one or more processors to
predict a response to chemoradiation treatment based on structural
deformation features and/or texture features of a pre-treatment
imaging volume of a rectum with rectal cancer, according to various
aspects discussed herein.
[0006] FIG. 2 illustrates a flow diagram of an example method/set
of operations that can be performed by one or more processors to
determine responsiveness to chemoradiation treatment based on
structural deformation features and/or texture features of a
post-treatment imaging volume of a rectum with rectal cancer,
according to various aspects discussed herein.
[0007] FIG. 3 illustrates a flow diagram of an example method/set
of operations that can be performed by one or more processors to
determine responsiveness to chemoradiation treatment based on
structural deformation features and/or texture features of a
post-treatment imaging volume of a rectum with rectal cancer,
according to various aspects discussed herein.
[0008] FIG. 4 illustrates a series of example diagrams showing
actions involved in extracting Structural Rectal Atlas Deformation
features from a patient MRI, according to various aspects discussed
herein.
[0009] FIG. 5 illustrates example diagrams and graphs associated
with predicting non-responders to chemoradiation via baseline MRIs
in the example use case, according to various aspects discussed
herein.
[0010] FIG. 6 illustrates example diagrams and graphs associated
with identifying good responders after chemoradiation via
post-therapy MRIs in the example use case, according to various
aspects discussed herein.
[0011] FIG. 7 illustrates a diagram of an example apparatus that
can facilitate prediction and/or identification of responding
and/or non-responding rectal cancer patients to chemoradiation
treatment and/or training a machine learning (ML) classifier to
perform such prediction and/or identification, according to various
embodiments discussed herein.
DETAILED DESCRIPTION
[0012] Various embodiments discussed herein can comprise techniques
that can facilitate determination of response of rectal cancer to
chemoradiation treatment based on pre-treatment medical imaging
(e.g., MRI (Magnetic Resonance Imaging)) and/or post-treatment
medical imaging of a patient. Based on mapping of a healthy rectal
atlas to the medical imaging of the patient, one or more structural
features can be determined. Based on a set of features comprising
the one or more structural features and/or one or more texture
features, a determination can be made regarding chemoradiation
response for the patient via a classifier trained on the set of
features.
[0013] Techniques discussed herein can be employed by various
embodiments to one or more of: (a) predict a response to
chemoradiation treatment from pre-treatment medical imaging of
rectal cancer, (b) determine whether rectal cancer is likely to
regress following chemoradiation treatment based on post-treatment
medical imaging of rectal cancer, or (c) train a classifier to
facilitate one or more of (a) or (b). The techniques discussed
herein comprise techniques that facilitate: (1) construction of a
healthy structural rectal atlas; (2) computing structural
deformations of medical imaging of a rectal cancer patient with
respect to the atlas; (3) extracting structural and/or texture
features from subregions within the rectal wall and/or peri-rectal
environment from the imaging of the patient; (4) training
classifier(s) to predict response to chemoradiation treatment
and/or determine tumor regression following chemoradiation
treatment; (5) predicting response or non-response to
chemoradiation treatment from baseline medical imaging; and/or (6)
identifying good or poor responders after chemoradiation treatment
from post-therapy medical imaging. Each of these techniques are
discussed in greater detail below, along with example application
of specific techniques in connection with a use case, although the
specific techniques employed can vary, depending on the
embodiment.
[0014] Some portions of the detailed descriptions that follow are
presented in terms of algorithms and symbolic representations of
operations on data bits within a memory. These algorithmic
descriptions and representations are used by those skilled in the
art to convey the substance of their work to others. An algorithm,
here and generally, is conceived to be a sequence of operations
that produce a result. The operations may include physical
manipulations of physical quantities. Usually, though not
necessarily, the physical quantities take the form of electrical or
magnetic signals capable of being stored, transferred, combined,
compared, and otherwise manipulated in a logic or circuit, and so
on. The physical manipulations create a concrete, tangible, useful,
real-world result.
[0015] It has proven convenient at times, principally for reasons
of common usage, to refer to these signals as bits, values,
elements, symbols, characters, terms, numbers, and so on. It should
be borne in mind, however, that these and similar terms are to be
associated with the appropriate physical quantities and are merely
convenient labels applied to these quantities. Unless specifically
stated otherwise, it is appreciated that throughout the
description, terms including processing, computing, calculating,
determining, and so on, refer to actions and processes of a
computer system, logic, circuit, processor, or similar electronic
device that manipulates and transforms data represented as physical
(electronic) quantities.
[0016] Example methods and operations may be better appreciated
with reference to flow diagrams. While for purposes of simplicity
of explanation, the illustrated methodologies are shown and
described as a series of blocks, it is to be appreciated that the
methodologies are not limited by the order of the blocks, as some
blocks can occur in different orders and/or concurrently with other
blocks from that shown and described. Moreover, less than all the
illustrated blocks may be required to implement an example
methodology. Blocks may be combined or separated into multiple
components. Furthermore, additional and/or alternative
methodologies can employ additional, not illustrated blocks.
[0017] Referring to FIG. 1, illustrated is a flow diagram of an
example method/set of operations 100 that can be performed by one
or more processors to predict a response to chemoradiation
treatment based on structural deformation features and/or texture
features of a pre-treatment imaging volume of a rectum with rectal
cancer, according to various aspects discussed herein. Processor(s)
can include any combination of general-purpose processors and
dedicated processors (e.g., graphics processors, application
processors, etc.). The one or more processors can be coupled with
and/or can include memory or storage and can be configured to
execute instructions stored in the memory or storage to enable
various apparatus, applications, or operating systems to perform
the operations. The memory or storage devices may include main
memory, disk storage, or any suitable combination thereof. The
memory or storage devices can comprise--but is not limited to--any
type of volatile or non-volatile memory such as dynamic random
access memory (DRAM), static random-access memory (SRAM), erasable
programmable read-only memory (EPROM), electrically erasable
programmable read-only memory (EEPROM), Flash memory, or
solid-state storage.
[0018] The set of operations 100 can comprise, at 110, accessing an
image volume of the rectum of a patient with rectal cancer, wherein
the image volume was obtained prior to chemoradiation treatment. In
various embodiments and in the example use case discussed below,
the image volume can comprise a Magnetic Resonance Imaging (MRI)
image volume. In other embodiments, other medical imaging
techniques can be employed to obtain the image volume. The image
volume can be obtained via a system and/or apparatus implementing
the set of operations 100, or can be obtained from a separate
medical imaging system. Additionally, the image volume can be
accessed contemporaneously with or at any point prior to performing
the set of operations 100.
[0019] The set of operations 100 can further comprise, at 120,
generating a forward mapping from a healthy rectal atlas (e.g.,
generated according to techniques discussed herein, etc.) to the
image volume via techniques discussed herein (e.g., via non-rigid
registration, etc.).
[0020] The set of operations 100 can further comprise, at 130,
inverting the forward mapping to generate an inverse mapping from
the image volume to the healthy rectal atlas.
[0021] The set of operations 100 can further comprise, at 140,
determining a deformation magnitude relative to the healthy rectal
atlas for each voxel of an intra-wall and/or peri-wall region of a
region of interest based on the inverse mapping (e.g., in one or
more sites N consecutive slices associated with a tumor, etc.).
[0022] The set of operations 100 can further comprise, at 150,
computing one or more structural deformation features from the
deformation magnitudes of intra-wall and/or peri-wall voxels. The
one or more structural deformation features can comprise
statistical measures of the intra-wall voxels and/or statistical
measures of the peri-wall voxels.
[0023] The set of operations 100 can further comprise, at 160,
optionally computing one or more texture features for the
intra-wall region and/or one or more texture features for the
peri-wall region.
[0024] The set of operations 100 can further comprise, at 170,
predicting a response to chemoradiation treatment based on the one
or more structural deformation features and/or the one or more
texture features via a classifier trained according to aspects
discussed herein.
[0025] Additionally or alternatively, set of operations 100 can
comprise one or more other actions discussed herein in connection
with predicting a response to chemoradiation treatment based on
pre-treatment medical imaging.
[0026] Referring to FIG. 2, illustrated is a flow diagram of an
example method/set of operations 200 that can be performed by one
or more processors to determine responsiveness to chemoradiation
treatment based on structural deformation features and/or texture
features of a post-treatment imaging volume of a rectum with rectal
cancer, according to various aspects discussed herein.
[0027] The set of operations 200 can comprise, at 210, accessing an
image volume of the rectum of a patient with rectal cancer, wherein
the image volume was obtained after chemoradiation treatment. In
various embodiments and in the example use case discussed below,
the image volume can comprise a MRI image volume. In other
embodiments, other medical imaging techniques can be employed to
obtain the image volume. The image volume can be obtained via a
system and/or apparatus implementing the set of operations 200, or
can be obtained from a separate medical imaging system.
Additionally, the image volume can be accessed contemporaneously
with or at any point prior to performing the set of operations
200.
[0028] The set of operations 200 can further comprise, at 220,
generating a forward mapping from a healthy rectal atlas (e.g.,
generated according to techniques discussed herein, etc.) to the
image volume via techniques discussed herein (e.g., via non-rigid
registration, etc.).
[0029] The set of operations 200 can further comprise, at 230,
inverting the forward mapping to generate an inverse mapping from
the image volume to the healthy rectal atlas.
[0030] The set of operations 200 can further comprise, at 240,
determining a deformation magnitude relative to the healthy rectal
atlas for each voxel of an intra-wall and/or peri-wall region of a
region of interest based on the inverse mapping (e.g., in one or
more sites comprising N consecutive slices associated with a tumor,
etc.).
[0031] The set of operations 200 can further comprise, at 250,
computing one or more structural deformation features from the
deformation magnitudes of intra-wall and/or peri-wall voxels. The
one or more structural deformation features can comprise
statistical measures of the intra-wall voxels and/or statistical
measures of the peri-wall voxels.
[0032] The set of operations 200 can further comprise, at 260,
optionally computing one or more texture features for the
intra-wall region and/or one or more texture features for the
peri-wall region.
[0033] The set of operations 200 can further comprise, at 270,
determining responsiveness to chemoradiation treatment (e.g.,
classification as a good responder or non-responder, etc.) based on
the one or more structural deformation features and/or the one or
more texture features via a classifier trained according to aspects
discussed herein.
[0034] Additionally or alternatively, set of operations 200 can
comprise one or more other actions discussed herein in connection
with determining responsiveness to chemoradiation treatment based
on post-treatment medical imaging.
[0035] Referring to FIG. 3, illustrated is a flow diagram of an
example method/set of operations 300 that can be performed by one
or more processors to train a Machine Learning (ML) classifier to
predict or determine responsiveness of rectal cancer to
chemoradiation treatment based on structural deformation and/or
texture features of pre- or post-treatment medical imaging,
according to various aspects discussed herein.
[0036] The set of operations 300 can comprise, at 310, optionally
constructing a healthy rectal atlas based on a set of image volumes
of healthy rectums, according to techniques discussed herein. In
other embodiments, a previously constructed healthy rectal atlas
can be employed by the set of operations 300. In various
embodiments and in the example use case discussed below, image
volumes employed by set of operations 300 can comprise MRI image
volumes. In other embodiments, other medical imaging techniques can
be employed to obtain the image volumes. The image volumes can be
obtained via a system and/or apparatus implementing the set of
operations 300, or can be obtained from a separate medical imaging
system. Additionally, the image volumes can be accessed
contemporaneously with or at any point prior to performing the set
of operations 300.
[0037] The set of operations 300 can further comprise, at 320,
accessing a training set of image volumes of rectums of patients
with rectal cancer. Each of the image volumes in the training set
can be associated with a known response to chemoradiation treatment
by the patient of that image volume. In some embodiments, each
image volume of the training set can comprise baseline imaging
taken prior to chemoradiation treatment, while in other
embodiments, each image volume of the training set can comprise
imaging taken after chemoradiation treatment.
[0038] The set of operations 300 can further comprise, at 330,
generating an associated forward mapping from a healthy rectal
atlas (e.g., generated according to techniques discussed herein,
etc.) to each image volume of the training set via techniques
discussed herein (e.g., via non-rigid registration, etc.).
[0039] The set of operations 300 can further comprise, at 340,
inverting the forward mapping for each image volume of the training
set of the training set to generate an inverse mapping from that
image volume to the healthy rectal atlas.
[0040] The set of operations 300 can further comprise, at 350,
determining a deformation magnitude relative to the healthy rectal
atlas for each voxel of an intra-wall and/or peri-wall region of a
region of interest of each image volume of the training set based
on the inverse mapping for that image volume (e.g., in one or more
sites of N consecutive slices associated with a tumor, etc.).
[0041] The set of operations 300 can further comprise, at 360,
computing one or more structural deformation features for each
image volume of the training set from the deformation magnitudes of
intra-wall and/or peri-wall voxels of that image volume. The one or
more structural deformation features can comprise statistical
measures of the intra-wall voxels and/or statistical measures of
the peri-wall voxels.
[0042] The set of operations 300 can further comprise, at 370, for
each image volume of the training set, optionally computing one or
more texture features for the intra-wall region of that image
volume and/or one or more texture features for the peri-wall region
of that image volume.
[0043] The set of operations 300 can further comprise, at 380,
determining one or more best features for characterizing response
to chemoradiation treatment based on the known responses to
chemoradiation treatment for the patients, the computed structural
deformation features for each image volume of the training set, and
optionally the computed texture features for each image volume of
the training set. Feature selection can be as discussed in
connection with the example use case, or can employ other feature
selection algorithms.
[0044] The set of operations 300 can further comprise, at 390,
constructing a machine learning (ML) classifier trained to classify
image volumes as responsive or non-responsive to chemoradiation
treatment based on values determined for that image volume for the
best features determined at 380.
[0045] Additionally or alternatively, set of operations 300 can
comprise one or more other actions discussed herein in connection
with training a classifier to predict or determine responsiveness
to chemoradiation treatment based on post-treatment medical
imaging.
[0046] Additional aspects and embodiments are discussed below in
connection with the following example use case.
Example Use Case: Structural Rectal Atlas Deformation Features for
Characterizing Intra- and Peri-Wall Chemoradiation Response on
MRI
[0047] The following discussion provides example embodiments in
connection with an example use case involving determination of
chemoradiation response in rectal cancer based on pre-treatment MRI
or based on post-treatment MRI via techniques discussed herein.
These techniques comprise: (1) construction of a healthy structural
rectal atlas; (2) computing structural deformations of medical
imaging of a rectal cancer patient with respect to the atlas; (3)
extracting structural and/or texture features from subregions
within the rectal wall and/or peri-rectal environment from the
imaging of the patient; (4) training classifier(s) to predict
response to chemoradiation treatment and/or determine tumor
regression following chemoradiation treatment; (5) predicting
response or non-response to chemoradiation treatment from baseline
medical imaging; or (6) identifying good or poor responders after
chemoradiation treatment from post-therapy medical imaging. Each of
techniques (1)-(6) are described in greater detail below. Although
specific details and aspects were employed for the example use case
as a specific concrete embodiment, it is to be appreciated that in
various embodiments, these details and aspects can vary.
A. Overview
[0048] Radiomic features which quantify morphologic texture and
shape of tumor regions on imaging have found wide success in
characterizing treatment response in vivo. A more detailed
interrogation of intra- and peri-tumoral regions for
response-related cues could be achieved by capturing subtle
structural deformations that occur due to tumor shrinkage or
growth. The example use case employed a set of Structural Rectal
Atlas Deformation features to quantify tumor-related deformations
in rectal cancers via a cohort of 139 patient MRIs. In flexible
non-rigid organs such as the rectum, inter-patient differences
complicate evaluation of tumor-related deformations that may occur
within the rectal wall or in the peri-rectal environment;
necessitating construction of a canonical rectal imaging atlas.
Using 63 pelvic MRIs where healthy rectums could be clearly
visualized, the example use case employed the first structural
atlas built for the healthy rectal wall. This atlas was used to
compute structural deformations within and around locations in the
rectal wall of patients where tumor was present, resulting in
intra- and peri-wall Structural Rectal Atlas Deformation
descriptors. The example use case evaluated the efficacy of these
Structural Rectal Atlas Deformation features in 2 different tasks:
(a) predicting which rectal tumors will or will not respond to
therapy via baseline MRIs (n=42), and (b) identifying which rectal
tumors were exhibiting regression on post-chemoradiation MRIs
(n=34). Using a linear discriminant analysis classifier in a
three-fold cross-validation scheme, it was found that intra-wall
deformations were significantly lower for responders to
chemoradiation; both on baseline MRIs (with AUC (Area Under ROC
(Receiver Operating Characteristic) Curve)=0.73.+-.0.05) as well as
on post-therapy MRIs (AUC=0.87.+-.0.03). By comparison, radiomic
texture features for both intra- and peri-wall locations yielded
significantly worse classification performance in both tasks.
[0049] As discussed above, for solid organs such as the brain or
prostate, new classes of features that quantify tissue deformations
or surface distensions on imaging have been linked to aggressive
tumor growth and tumor recurrence. Quantifying such structural
changes in more flexible organs such as the rectum requires
construction of a healthy rectal wall atlas (e.g., the rectal
anatomy without a tumor). In connection with the example use case,
it was hypothesized that constructing a healthy rectal atlas could
then allow for a unique quantification of disease-specific
structural changes in the rectal environment (wall/tumor,
peri-wall/tumor) that may be closely related to tumor response to
therapy. The hypothesis was tested via the following aspects of the
example use case (discussed in greater detail below): (1)
Development of the first structural atlas representation for
healthy rectal wall anatomy, via a multi-stage registration scheme
using pelvic MRIs (from other cancers) where normal rectums are
visible and (2) The first attempt at relating subtle structural
deformations occurring within and around rectal wall regions to
chemoradiation-related tumor growth or shrinkage in vivo.
[0050] The Structural Rectal Atlas Deformation features discussed
herein were evaluated in the context of two distinct clinical
problems in rectal cancer: (a) prediction of pathologic
non-responders to chemoradiation via baseline treatment-naive MRI,
and (b) assessment of pathologic responders on post-chemoradiation
MRI. Together, these two problems represent the major clinical
challenges facing personalization of patient management in rectal
cancers.
B. Methodology
[0051] Quantifying structural deformations within and around the
rectum involves the following 3 acts: (i) building a structural
atlas for normal rectal wall anatomy on imaging, (ii) computing
structural deformations of the rectal wall in patients with tumors
with respect to this atlas, and (iii) extracting tumor-related
structural deformation descriptors within the rectal wall and
peri-rectal environment.
[0052] Referring to FIG. 4, illustrated is a series of example
diagrams 400 showing actions involved in extracting Structural
Rectal Atlas Deformation features from a patient MRI, according to
various aspects discussed herein. At 410, a set of healthy rectum
MRI images with annotated rectal walls (e.g., via expert
annotation, etc) can be obtained. At 420, a healthy rectal atlas
can be constructed from the healthy rectum MRI images according to
techniques discussed herein. At 430, a forward mapping from the
atlas to the MRI of a rectal cancer patient can be determined. At
440, based on the forward mapping, an inverse mapping from the MRI
of the patient to the atlas can be determined, based on which
deformations within and around the rectal wall with respect to the
atlas can be determined. At 450, based on the determined
deformations, structural deformation features can be extracted for
an intra-wall and/or peri-wall region of the MRI of the
patient.
Construction of Structural Rectal Atlas
[0053] A set of N MRI scenes depicting the healthy rectum was
utilized, and denoted X=(C, f), where C is a 3-dimensional spatial
grid and f(c) represents the MRI intensity at each voxel c.di-elect
cons.C. The primary anatomic region defined within this MRI scene
is the healthy rectal wall, denoted X.sup.r=(C, f.sup.r), where
f.sup.r(c)=1 within the rectal wall and zero in the rest of the
scene. X.sup.r can be identified and annotated by experts on all X,
and is depicted in the images of 410 in FIG. 4.
[0054] The final output of this construction is the healthy rectal
wall atlas, denoted A=(C, g.sup.r), with g.sup.r(c).di-elect
cons.[0,1] defined as the frequency of a particular location
c.di-elect cons.C where f.sup.r(c)=1 (e.g., corresponding to rectal
wall); across N different input subject scenes. These N different
subject scenes were aligned to a registration template for
projection into a canonical space to construct A, via the following
three transformations.
[0055] The first transformation can be a simple transformation,
.tau..sub..rho., that is used to map N different subject scenes X
such that they are all centered and isotropically scaled in the X,
Y, and Z axes. The resulting initial atlas, A.sub..rho., is
therefore not dependent on selecting a specific subject as the
template and can be constructed such that A.sub..rho.=(C, g.sup.r),
where
g r ( c ) = 1 N .SIGMA. N f r ( c ) , ##EQU00001##
for every location c.di-elect cons.C, across all N studies after
.tau..sub..rho. has been applied (e.g., g.sup.r(c) is the frequency
of a location corresponding to the rectal wall).
[0056] In the second transformation, affine registration can be
used to compute .tau..sub..alpha. for projecting all X onto
A.sub..rho.. The affinely transformed subject scenes can be used to
construct A.sub..alpha.=(C, g.sup.r) (based on re-computing
g.sup.r(c).A-inverted.c.di-elect cons.C, across all N studies).
[0057] In the third transformation, deformable registration can be
used to align X to A.sub..alpha.. The final structural rectal atlas
A=(C, g.sup.r), can be constructed based on re-computing
g.sup.r(c).A-inverted.c.di-elect cons.C, across N deformed subject
scenes.
Computing Structural Deformations with Respect to the Atlas
[0058] Given a rectal cancer patient MRI scene, denoted I,
structural deformations in the rectal environment can be quantified
with respect to the healthy atlas A. The rectal wall within the
patient MRI scene is denoted I.sup.r. First, A can be non-rigidly
registered to I using a normalized mutual information-based
similarity measure within a b-spline registration scheme. This
non-rigid alignment can be formulated as (I.sup.r, I)=T(A), where T
is the forward transformation of the composite voxel-wise
deformation field (comprising affine and deformable components)
that maps the rectal wall between the reference (I.sup.r) and
floating (A) volumes. This transformation can then be inverted to
yield T.sup.-1, which can be used to map I into the A space. This
two-stage mapping process can be employed to compute structural
deformations within I with respect to A at every c.di-elect cons.C,
hypothesized to occur as a result of tumor-related growth or
shrinkage of the rectal wall.
Extracting Structural Rectal Atlas Deformation (StRAD) Descriptors
for Subregions Within Rectal Wall and Peri-Rectal Environment
[0059] Structural deformations can be quantified for each rectal
cancer patient scene within I.sup.r, as well for a peri-wall area
denoted I.sup.p. The latter was defined based on I.sup.r within
each of the experiments later conducted. Once I is mapped to the A
space, all voxel positions (c.sub.x,c.sub.y,c.sub.z) can be assumed
to be displaced by [.delta..sub.x,.delta..sub.y,.delta..sub.z], to
result in
(c'.sub.x,c'.sub.y,c'.sub.z)=(c.sub.x,c.sub.y,c.sub.z)+[.delta..sub.x,.de-
lta..sub.y,.delta..sub.z]. Based on this displacement vector, the
deformation magnitude can be computed as D(c)= {square root over
((.delta..sub.x).sup.2+(.delta..sub.y).sup.2+(.delta..sub.z).sup.2)},
for every c.di-elect cons.C. The descriptor .sub.def.sup.r for
intra-wall deformations can comprise first order statistics (e.g.,
mean, median, standard deviation, skewness, and kurtosis) of D(c)
for all the voxels c within the rectal wall I.sup.r. Similarly, the
peri-wall deformation descriptor .sup.r.sub.def can be computed
based on first-order statistics of the deformation magnitudes in
I.sup.p.
Experimental Design
Data Description
[0060] Healthy rectum cohort (S.sub.1): A cohort of 63 patients who
had been diagnosed with prostate cancer and had undergone an axial
pelvic MRI scan were curated. These scans were selected based on
having the healthy rectal wall being clearly visible, as no
endorectal coil had been used.
[0061] Baseline RCa cohort (S.sub.2): A cohort of 42 patients who
had been diagnosed with rectal cancer were identified, all of whom
had undergone axial 3 Tesla (T) T2w MR imaging before
standard-of-care chemoradiation. A first objective of the example
use case was to predict non-responders to chemoradiation using this
baseline MRI scan. Pathologic tumor stage (T-stage, based on
excised rectal specimens) was used as a marker of response, where
ypT3-4 corresponded to extensive tumor being present in the
specimen despite chemoradiation. Based on this pathologic
classification, n=22 patients were identified as being
non-responsive to chemoradiation (ypT3-4), and the remainder as
good responders to chemoradiation (ypT0-2, n=20).
[0062] Post-therapy RCa cohort (S.sub.3): A separate cohort of 34
RCa patients was curated, where patients had axial 3 T T2w MRIs
available after undergoing standard-of-care chemoradiation but
prior to excision surgery. In this cohort, the goal was to identify
which patients exhibited marked tumor regression (based on
pathologic T-stage) via the post-therapy MRI scan. With ypT0-2
indicating minimal or dying tumor within the rectal wall after
chemoradiation, n=17 patients were assessed as being good
responders and the remaining n=17 were classified as exhibiting
minimal or no response to chemoradiation (ypT3-4).
Implementation Details
[0063] For all 139 MRI scans in cohorts S.sub.1-3, the entire
length of the visible rectal wall from the anus to the peritoneal
reflection was annotated by an expert radiologist. For the 76 RCa
cases in S.sub.2 and S.sub.3, the slices most suspicious for tumor
presence were also identified by the radiologist (using anatomic
information from pathology reports). The healthy atlas A was
constructed using N=63 MRI pelvic scans in S.sub.1 using the
approach discussed herein. Evaluation of the atlas in terms of
overlap in annotated rectal wall as well as internal lumen regions
(across all patients in S.sub.1 after deformable mapping) yielded a
Dice similarity coefficient of 0.87, indicating A was a relatively
accurate representation.
[0064] Deformation fields for the remaining 79 RCa scans in S.sub.2
and S.sub.3 (with respect to A) were then computed to yield
intra-wall and peri-wall StRAD descriptors, .sub.def.sup.r and
.sub.def.sup.p, respectively (each a 5.times.1 vector in the
example use case, although the size can vary in different
embodiments). The peri-wall region was empirically defined as an 8
pixel band along the outer wall boundary for S.sub.2 and S.sub.3.
All registration steps were implemented using elastix, with a grid
spacing of 9.times.9.times.9 (in the example use case, although the
size can vary in different embodiments) when computing b-spline
deformations. Radiomic texture features were also extracted to
characterize the appearance of intra- and peri-wall areas on all 79
RCa scans, yielding .sub.tex.sup.r and .sub.tex.sup.p (each a
825.times.1 vector in the example use case, although the size can
vary in different embodiments). Both deformation and texture
features were extracted from 3 consecutive slices (the number of
slices can vary depending on the embodiment) comprising the largest
wall area suspicious for tumor, assuming that this region was most
likely to exhibit signatures related to tumor growth or shrinkage
on MRI.
[0065] Separate experiments were conducted using each of S.sub.2
and S.sub.3 in a cross-validation setting, with the goal of
distinguishing between the 2 patient groups in each cohort.
Following feature extraction, minimum redundancy maximum relevance
feature selection (mRMR) was used to identify the 3 most relevant
features (although a different number could be employed in various
embodiments) within each of .sub.def.sup.r, .sub.def.sup.p,
.sub.tex.sup.r, and .sub.tex.sup.p. The most relevant set of
features from each vector was then evaluated via a Linear
Discriminant Analysis (LDA) classifier (although other machine
learning classifiers can be employed in various embodiments, e.g.,
Quadratic Discriminant Analysis (QDA), Support Vector Machine
(SVM), Random Forest (RF), etc.). A total of 50 iterations (in
various embodiments, the number of iterations can vary) of a
three-fold (e.g., with one fold held-out for testing),
patient-stratified, cross-validation scheme were utilized to ensure
robustness of feature selection and classifier evaluation steps;
with Receiver Operating Characteristic (ROC) analysis for
evaluation. These steps were repeated for each of S.sub.2 and
S.sub.3, and the area under the ROC curve (AUC) across all
cross-validation runs was used to compare each of .sub.def.sup.r,
.sub.def.sup.p, .sub.tex.sup.r, and .sub.tex.sup.p (via Wilcoxon
ranksum testing, although other feature selecting algorithms can be
employed in various embodiments) to determine which feature set was
most relevant for treatment response characterization.
Results and Discussion
Experiment 1: Predicting Non-Responders to Chemoradiation via
Baseline MRIs
[0066] The most relevant StRAD descriptors identified in
experimental evaluation of S.sub.2 were the skewness and standard
deviation of intra-wall deformation magnitudes. Referring to FIG.
5, illustrated are example diagrams and graphs associated with
predicting non-responders to chemoradiation via baseline MRIs in
the example use case, according to various aspects discussed
herein. At 510 and 530 are representative baseline T2w MRI scans
from S.sub.2 for two different patients showing the deformation
field as colored arrows within the rectal wall (annotated in 510
and 530). At 520 and 540, the corresponding intra-wall deformation
magnitudes for 510 and 530, respectively, are visualized as a
heatmap, where higher values/shades correspond to higher D(c). At
550, boxplots of skewness in deformation magnitudes reveal
intra-wall deformations in non-responders to chemoradiation are
positively skewed (e.g., having larger magnitudes in NR patients,
ypT3-4) compared to good responders (GR). At 560, a bar plot of AUC
values is presented for different feature descriptors, showing that
.sub.def .sup.r resulted in a significantly higher performance than
.sub.def.sup.p, .sub.tex.sup.r, and .sub.tex.sup.p. The results of
the first experiment indicate that non-responders to chemoradiation
may be associated with significantly higher structural deformations
within the rectal wall on baseline MRI scans (as seen at 550,
showing positive skew associated with non-responders), when
compared to the healthy rectal atlas. This resonates with previous
findings where it has been reported that smaller rectal tumors tend
to respond favorably to chemoradiation, which would result in their
being associated with less pronounced wall deformations (with
reference to a healthy atlas). Further, the intra-wall StRAD
descriptor (.sub.def.sup.r) also yielded the best overall AUC in
this classification task (.sub.def.sup.r is shown in the leftmost
bar of 560, with a AUC of 0.73.+-.0.05). This was significantly
higher (p<0.001) than the AUCs for each of .sub.def.sup.p,
.sub.tex.sup.r, and .sub.tex.sup.p.
Experiment 2: Identifying Good Responders After Chemoradiation via
Post-Therapy MRIs
[0067] In S.sub.3, the median and standard deviation of the
intra-wall deformation magnitude were identified as the most
relevant StRAD descriptors. Referring to FIG. 6, illustrated are
example diagrams and graphs associated with identifying good
responders after chemoradiation via post-therapy MRIs in the
example use case, according to various aspects discussed herein. At
610 and 630 are representative post-therapy T2w MRI scans from
S.sub.3 for two different patients showing the deformation field
visualized as arrows within the annotated outline of the rectal
wall. At 620 and 640 are the corresponding intra-wall deformation
magnitudes for the patients of 610 and 630, respectively,
visualized as heatmaps, where higher values/shades correspond to
higher D(c). At 650, boxplots of standard deviation of deformation
magnitudes within the rectal wall reveal significantly less
variable deformations associated with good responders to
chemoradiation (GR, ypT0-2) compared to non-responders (NR). At
660, a bar plot of AUC values is presented for different feature
descriptors, showing that .sub.def.sup.r resulted in a
significantly higher performance than .sub.def.sup.p,
.sub.tex.sup.r, and .sub.tex.sup.p. As can be seen from FIG. 6,
good responders are associated with significantly lower and less
variable structural intra-wall deformations. As non-responders
(e.g., ypT3-4) are likely to have more tumor extent outside the
rectal wall despite chemoradiation, this would be reflected in the
rectal wall being more deformed with respect to the healthy rectal
atlas. The intra-wall StRAD descriptor (.sub.def.sup.r)
significantly outperformed all of .sub.def.sup.p, .sub.tex.sup.r,
and .sub.tex.sup.p in terms of AUC values for this classification
task, with an AUC of 0.87.+-.0:03, p<0.001, as shown at 660.
Conclusion
[0068] The example use case presented a novel suite of STructural
Rectal Atlas Deformation (StRAD) features for characterizing intra-
and peri-wall response to chemoradiation on rectal MRIs. The
example use case involved construction of the first reference
healthy rectal wall atlas, which was applied to compute
tumor-related deformations on baseline and post-chemoradiation
MRIs, separately. StRAD features from within the rectal wall were
found to be most effective for characterizing tumor treatment
response on MRI, revealing that non-responder RCa patients in both
pre- and post-therapy settings were associated with significantly
higher and more variable intra-wall deformations; likely occurring
as a result of more aggressive tumor growth. By contrast,
morphologic texture features performed significantly worse both for
predicting as well as evaluating response to therapy via MRI. The
example use case provides specific examples of embodiments, but it
is to be understood that other embodiments can vary from those of
the example use case in one or more aspects, including as discussed
herein. Various embodiments can employ StRAD features validated on
a larger cohort of data, including multiple sites, as well as
evaluation of parameter sensitivity. Additionally, various
embodiments can integrate StRAD featues with other morphologic
descriptors and clinical variables to reliably predict and assess
treatment response for rectal cancers in vivo.
Additional Embodiments
[0069] In various example embodiments, method(s) discussed herein
can be implemented as computer executable instructions. Thus, in
various embodiments, a computer-readable storage device can store
computer executable instructions that, when executed by a machine
(e.g., computer, processor), cause the machine to perform methods
or operations described or claimed herein including operation(s)
described in connection with methods 100, 200, 300, 400 or any
other methods or operations described herein. While executable
instructions associated with the listed methods are described as
being stored on a computer-readable storage device, it is to be
appreciated that executable instructions associated with other
example methods or operations described or claimed herein can also
be stored on a computer-readable storage device. In different
embodiments, the example methods or operations described herein can
be triggered in different ways. In one embodiment, a method or
operation can be triggered manually by a user. In another example,
a method or operation can be triggered automatically.
[0070] Embodiments discussed herein relate to training and/or
employing classifiers to predict or determine a likelihood of
response to chemoradiation treatment based on structural
deformation and/or texture features associated with rectal cancer
in a MRI image volume that are not perceivable by the human eye,
and involve computation that cannot be practically performed in the
human mind. As one example, machine learning and/or deep learning
classifiers as described herein cannot be implemented in the human
mind or with pencil and paper. Embodiments thus perform actions,
steps, processes, or other actions that are not practically
performed in the human mind, at least because they require a
processor or circuitry to access digitized images stored in a
computer memory and to extract or compute features that are based
on the digitized images and not on properties of tissue or the
images that are perceivable by the human eye. Embodiments described
herein can use a combined order of specific rules, elements,
operations, or components that render information into a specific
format that can then be used and applied to create desired results
more accurately, more consistently, and with greater reliability
than existing approaches, thereby producing the technical effect of
improving the performance of the machine, computer, or system with
which embodiments are implemented.
[0071] Referring to FIG. 7, illustrated is a diagram of an example
apparatus 700 that can facilitate prediction and/or identification
of responding and/or non-responding rectal cancer patients to
chemoradiation treatment and/or training a machine learning (ML)
classifier to perform such prediction and/or identification,
according to various embodiments discussed herein. Apparatus 700
can be configured to perform various techniques discussed herein,
for example, various operations discussed in connection with sets
of operations 100, 200, 300, and/or 400. Apparatus 700 can comprise
one or more processors 710 and memory 720. Processor(s) 710 can, in
various embodiments, comprise circuitry such as, but not limited
to, one or more single-core or multi-core processors. Processor(s)
710 can include any combination of general-purpose processors and
dedicated processors (e.g., graphics processors, application
processors, etc.). The processor(s) can be coupled with and/or can
comprise memory (e.g., of memory 720) or storage and can be
configured to execute instructions stored in the memory 720 or
storage to enable various apparatus, applications, or operating
systems to perform operations and/or methods discussed herein.
Memory 720 can be configured to store one or more image volumes
(e.g., MRI, etc.) of a rectum, for example, a rectum of a patient
with rectal cancer (e.g., for training and/or classification), or a
healthy rectum (e.g., for construction of a rectal atlas). Each of
the image(s) of the image volume can comprise a plurality of pixels
or voxels, each pixel or voxel having an associated intensity.
Memory 720 can be further configured to store additional data
involved in performing operations discussed herein, such as for
determining response to chemoradiation treatment of a rectal cancer
patient and/or training a ML or DL model to determine response to
chemoradiation treatment of a rectal cancer patient, as discussed
in greater detail herein.
[0072] Apparatus 700 can also comprise an input/output (I/O)
interface 730 (e.g., associated with one or more I/O devices), a
set of circuits 750, and an interface 740 that connects the
processor(s) 710, the memory 720, the I/O interface 730, and the
set of circuits 750. I/O interface 730 can be configured to
transfer data between memory 720, processor 710, circuits 750, and
external devices, for example, a medical imaging device (e.g., MRI
system or apparatus, etc.), and/or one or more remote devices for
receiving inputs and/or providing outputs to a clinician, patient,
etc., such as optional personalized medicine device 760.
[0073] The processor(s) 710 and/or one or more circuits of the set
of circuits 750 can perform one or more acts associated with a
method or set of operations discussed herein, such as set of
operations 100, 200, 300, or 400. In various embodiments, different
acts (e.g., different operations of a set of operations) can be
performed by the same or different processor(s) 710 and/or one or
more circuits of the set of circuits 750.
[0074] Apparatus 700 can optionally further comprise personalized
medicine device 760. Apparatus 700 can be configured to provide the
determination or prediction of response to chemoradiation treatment
for a rectal cancer patient, or other data to personalized medicine
device 760. Personalized medicine device 760 may be, for example, a
computer assisted diagnosis (CADx) system or other type of
personalized medicine device that can be used to facilitate
monitoring and/or treatment of an associated medical condition. In
some embodiments, processor(s) 710 and/or one or more circuits of
the set of circuits 750 can be further configured to control
personalized medicine device 760 to display the determination or
prediction of response to chemoradiation treatment for the patient
or other data on a computer monitor, a smartphone display, a tablet
display, or other displays.
[0075] Examples herein can include subject matter such as an
apparatus, an MRI system, a CT system, a personalized medicine
system, a CADx system, a processor, a system, circuitry, a method,
means for performing acts, steps, or blocks of the method, at least
one machine-readable medium including executable instructions that,
when performed by a machine (e.g., a processor with memory, an
application-specific integrated circuit (ASIC), a field
programmable gate array (FPGA), or the like) cause the machine to
perform acts of the method or of an apparatus or system for
generating system-independent quantitative perfusion measurements,
according to embodiments and examples described.
[0076] Example 1 is a non-transitory computer-readable medium
storing computer-executable instructions that, when executed, cause
a processor to perform operations, comprising: accessing an image
volume of a rectum comprising a rectal tumor, wherein the image
volume was obtained prior to a chemoradiation treatment of the
rectal tumor; generating a forward mapping based on non-rigidly
registering a healthy rectal atlas to the image volume; inverting
the forward mapping to generate an inverse mapping from the image
volume to the healthy rectal atlas; determining, based on the
inverse mapping, an associated deformation magnitude for each voxel
of a plurality of voxels associated with the rectum; computing one
or more structural deformation features based on the associated
deformation magnitudes for the plurality of voxels; and predicting
via a classifier whether or not the rectal tumor will respond to
the chemoradiation treatment based at least in part on the one or
more structural deformation features.
[0077] Example 2 comprises the subject matter of any variation of
any of example(s) 1, wherein the image volume is a Magnetic
Resonance Imaging (MRI) image volume.
[0078] Example 3 comprises the subject matter of any variation of
any of example(s) 1-2, wherein the classifier is one of a Linear
Discriminant Analysis (LDA) classifier, a Quadratic Discriminant
Analysis (QDA) classifier, a Support Vector Machine (SVM)
classifier, or a Random Forest (RF) classifier.
[0079] Example 4 comprises the subject matter of any variation of
any of example(s) 1-3, wherein the one or more structural
deformation features comprise one or more intra-wall deformation
features associated with a wall of the rectum.
[0080] Example 5 comprises the subject matter of any variation of
any of example(s) 4, wherein the operations further comprise
computing one or more peri-wall texture features associated with a
peri-wall region near a wall of the rectum, wherein the predicting
via the classifier is based at least in part on the one or more
peri-wall texture features.
[0081] Example 6 comprises the subject matter of any variation of
any of example(s) 1-5, wherein the one or more structural
deformation features comprise one or more peri-wall deformation
features associated with a peri-wall region near a wall of the
rectum.
[0082] Example 7 comprises the subject matter of any variation of
any of example(s) 6, wherein the operations further comprise
computing one or more intra-wall texture features associated with a
wall of the rectum, wherein the predicting via the classifier is
based at least in part on the one or more intra-wall texture
features.
[0083] Example 8 comprises the subject matter of any variation of
any of example(s) 1-7, wherein the one or more structural
deformation features comprise one or more of the following computed
for at least a subset of the plurality of voxels: a mean of the
deformation magnitude, a median of the deformation magnitude, a
standard deviation of the deformation magnitude, a skewness of the
deformation magnitude, or a kurtosis of the deformation
magnitude.
[0084] Example 9 comprises the subject matter of any variation of
any of example(s) 1-8, wherein the operations further comprise
computing one or more texture features based on the plurality of
voxels, wherein the predicting via the classifier is based at least
in part on the one or more texture features.
[0085] Example 10 comprises the subject matter of any variation of
any of example(s) 9, wherein the one or more texture features
comprise one or more of at least one intra-wall texture feature
associated with a wall of the rectum or at least one peri-wall
texture feature associated with a peri-wall region near the wall of
the rectum.
[0086] Example 11 is a non-transitory computer-readable medium
storing computer-executable instructions that, when executed, cause
a processor to perform operations, comprising: accessing an image
volume of a rectum comprising a rectal tumor, wherein the image
volume was obtained after a chemoradiation treatment of the rectal
tumor; generating a forward mapping based on non-rigidly
registering a healthy rectal atlas to the image volume; inverting
the forward mapping to generate an inverse mapping from the image
volume to the healthy rectal atlas; determining, based on the
inverse mapping, an associated deformation magnitude for each voxel
of a plurality of voxels associated with the rectum; computing one
or more structural deformation features based on the associated
deformation magnitudes for the plurality of voxels; and
determining, via a classifier, whether or not the rectal tumor is
responsive to the chemoradiation treatment based at least in part
on the one or more structural deformation features.
[0087] Example 12 comprises the subject matter of any variation of
any of example(s) 11, wherein the image volume is a Magnetic
Resonance Imaging (MRI) image volume.
[0088] Example 13 comprises the subject matter of any variation of
any of example(s) 11-12, wherein the classifier is one of a Linear
Discriminant Analysis (LDA) classifier, a Quadratic Discriminant
Analysis (QDA) classifier, a Support Vector Machine (SVM)
classifier, or a Random Forest (RF) classifier.
[0089] Example 14 comprises the subject matter of any variation of
any of example(s) 11-13, wherein the one or more structural
deformation features comprise one or more intra-wall deformation
features associated with a wall of the rectum.
[0090] Example 15 comprises the subject matter of any variation of
any of example(s) 14, wherein the operations further comprise
computing one or more peri-wall texture features associated with a
peri-wall region near a wall of the rectum, wherein the predicting
via the classifier is based at least in part on the one or more
peri-wall texture features.
[0091] Example 16 comprises the subject matter of any variation of
any of example(s) 11-15, wherein the one or more structural
deformation features comprise one or more peri-wall deformation
features associated with a peri-wall region near a wall of the
rectum.
[0092] Example 17 comprises the subject matter of any variation of
any of example(s) 16, wherein the operations further comprise
computing one or more intra-wall texture features associated with a
wall of the rectum, wherein the predicting via the classifier is
based at least in part on the one or more intra-wall texture
features.
[0093] Example 18 comprises the subject matter of any variation of
any of example(s) 11-17, wherein the one or more structural
deformation features comprise one or more of the following computed
for at least a subset of the plurality of voxels: a mean of the
deformation magnitude, a median of the deformation magnitude, a
standard deviation of the deformation magnitude, a skewness of the
deformation magnitude, or a kurtosis of the deformation
magnitude.
[0094] Example 19 comprises the subject matter of any variation of
any of example(s) 11-18, wherein the operations further comprise
computing one or more texture features based on the plurality of
voxels, wherein the predicting via the classifier is based at least
in part on the one or more texture features.
[0095] Example 20 comprises the subject matter of any variation of
any of example(s) 19, wherein the one or more texture features
comprise one or more of at least one intra-wall texture feature
associated with a wall of the rectum or at least one peri-wall
texture feature associated with a peri-wall region near the wall of
the rectum.
[0096] Example 21 is a non-transitory computer-readable medium
storing computer-executable instructions that, when executed, cause
a processor to perform operations, comprising: accessing a
plurality of training image volumes, wherein each image volume of
the plurality of training image volumes comprises an associated
rectum comprising an associated rectal tumor of that image volume,
and wherein each image volume of the plurality of training image
volumes has an associated known response to a chemoradiation
treatment; for each image volume of the plurality of training image
volumes: generating an associated forward mapping for that image
volume based on non-rigidly registering a healthy rectal atlas to
that image volume; invert the associated forward mapping to
generate an associated inverse mapping for that image volume from
that image volume to the healthy rectal atlas; determining, based
on the associated inverse mapping for that image volume, an
associated deformation magnitude for each voxel of a plurality of
voxels associated with the associated rectum of that image volume;
and computing, based on the associated deformation magnitudes for
the plurality of voxels associated with the associated rectum of
that image volume, an associated value for that image volume for
each structural deformation feature of a plurality of structural
deformation features; determining one or more best features for
characterizing response to the chemoradiation treatment from among
a set of features comprising the plurality of structural
deformation features and a plurality of texture features, wherein
the one or more best features are determined based at least on: the
associated known responses for the plurality of training image
volumes and the associated values for the plurality of training
image volumes for the plurality of structural deformation features;
and constructing a classifier configured to classify an additional
image volume comprising an associated rectum with an associated
rectal tumor as responsive or non-responsive to the chemoradiation
treatment based at least on the one or more best features.
[0097] Example 22 comprises the subject matter of any variation of
any of example(s) 21, wherein the operations further comprise
computing, based on the plurality of voxels associated with the
associated rectum of that image volume, an associated value for
that image volume for each texture feature of the plurality of
texture features, and wherein the one or more best features are
determined based at least on the associated values for the
plurality of training image volumes for the plurality of texture
features.
[0098] Example 23 comprises the subject matter of any variation of
any of example(s) 22, wherein the plurality of texture features
comprise one or more of at least one intra-wall texture feature
computed for that image volume from an associated wall of the
associated rectum of that image volume or at least one peri-wall
texture feature computed for that image volume from an associated
peri-wall region near the associated wall of the rectum of the
associated rectum of that image volume.
[0099] Example 24 comprises the subject matter of any variation of
any of example(s) 21-23, wherein the operations further comprise:
accessing a plurality of healthy image volumes, wherein each image
volume of the plurality of healthy image volumes comprises an
associated healthy rectum of that image volume, and wherein an
associated rectal wall of the associated healthy rectum of that
image volume has been annotated; and generating a healthy rectal
wall atlas based on the associated rectal wall of the associated
healthy rectum of each image volume of the plurality of healthy
image volumes.
[0100] Example 25 comprises the subject matter of any variation of
any of example(s) 21-24, wherein the plurality of training image
volumes is a plurality of Magnetic Resonance Imaging (MRI) image
volumes.
[0101] Example 26 comprises the subject matter of any variation of
any of example(s) 21-25, wherein the classifier is one of a Linear
Discriminant Analysis (LDA) classifier, a Quadratic Discriminant
Analysis (QDA) classifier, a Support Vector Machine (SVM)
classifier, or a Random Forest (RF) classifier.
[0102] Example 27 comprises the subject matter of any variation of
any of example(s) 21-26, wherein the plurality of structural
deformation features comprise one or more intra-wall deformation
features computed for that image volume from an associated wall of
the associated rectum of that image volume.
[0103] Example 28 comprises the subject matter of any variation of
any of example(s) 21-27, wherein the plurality of structural
deformation features comprise one or more peri-wall deformation
features computed for that image volume from an associated
peri-wall region near an associated wall of the associated rectum
of that image volume.
[0104] Example 29 comprises the subject matter of any variation of
any of example(s) 21-28, wherein the plurality of structural
deformation features comprise one or more of the following computed
for at least a subset of the plurality of voxels: a mean of the
deformation magnitude, a median of the deformation magnitude, a
standard deviation of the deformation magnitude, a skewness of the
deformation magnitude, or a kurtosis of the deformation
magnitude.
[0105] Example 30 comprises an apparatus comprising means for
executing any of the described operations of examples 1-29.
[0106] Example 31 comprises a machine readable medium that stores
instructions for execution by a processor to perform any of the
described operations of examples 1-29.
[0107] Example 32 comprises an apparatus comprising: a memory; and
one or more processors configured to: perform any of the described
operations of examples 1-29.
[0108] References to "one embodiment", "an embodiment", "one
example", and "an example" indicate that the embodiment(s) or
example(s) so described may include a particular feature,
structure, characteristic, property, element, or limitation, but
that not every embodiment or example necessarily includes that
particular feature, structure, characteristic, property, element or
limitation. Furthermore, repeated use of the phrase "in one
embodiment" does not necessarily refer to the same embodiment,
though it may.
[0109] "Computer-readable storage device", as used herein, refers
to a device that stores instructions or data. "Computer-readable
storage device" does not refer to propagated signals. A
computer-readable storage device may take forms, including, but not
limited to, non-volatile media, and volatile media. Non-volatile
media may include, for example, optical disks, magnetic disks,
tapes, and other media. Volatile media may include, for example,
semiconductor memories, dynamic memory, and other media. Common
forms of a computer-readable storage device may include, but are
not limited to, a floppy disk, a flexible disk, a hard disk, a
magnetic tape, other magnetic medium, an application specific
integrated circuit (ASIC), a compact disk (CD), other optical
medium, a random access memory (RAM), a read only memory (ROM), a
memory chip or card, a memory stick, and other media from which a
computer, a processor or other electronic device can read.
[0110] "Circuit", as used herein, includes but is not limited to
hardware, firmware, software in execution on a machine, or
combinations of each to perform a function(s) or an action(s), or
to cause a function or action from another logic, method, or
system. A circuit may include a software controlled microprocessor,
a discrete logic (e.g., ASIC), an analog circuit, a digital
circuit, a programmed logic device, a memory device containing
instructions, and other physical devices. A circuit may include one
or more gates, combinations of gates, or other circuit components.
Where multiple logical circuits are described, it may be possible
to incorporate the multiple logical circuits into one physical
circuit. Similarly, where a single logical circuit is described, it
may be possible to distribute that single logical circuit between
multiple physical circuits.
[0111] To the extent that the term "includes" or "including" is
employed in the detailed description or the claims, it is intended
to be inclusive in a manner similar to the term "comprising" as
that term is interpreted when employed as a transitional word in a
claim.
[0112] Throughout this specification and the claims that follow,
unless the context requires otherwise, the words `comprise` and
`include` and variations such as `comprising` and `including` will
be understood to be terms of inclusion and not exclusion. For
example, when such terms are used to refer to a stated integer or
group of integers, such terms do not imply the exclusion of any
other integer or group of integers.
[0113] To the extent that the term "or" is employed in the detailed
description or claims (e.g., A or B) it is intended to mean "A or B
or both". When the applicants intend to indicate "only A or B but
not both" then the term "only A or B but not both" will be
employed. Thus, use of the term "or" herein is the inclusive, and
not the exclusive use. See, Bryan A. Garner, A Dictionary of Modern
Legal Usage 624 (2d. Ed. 1995).
[0114] While example systems, methods, and other embodiments have
been illustrated by describing examples, and while the examples
have been described in considerable detail, it is not the intention
of the applicants to restrict or in any way limit the scope of the
appended claims to such detail. It is, of course, not possible to
describe every conceivable combination of components or
methodologies for purposes of describing the systems, methods, and
other embodiments described herein. Therefore, the invention is not
limited to the specific details, the representative apparatus, and
illustrative examples shown and described. Thus, this application
is intended to embrace alterations, modifications, and variations
that fall within the scope of the appended claims.
* * * * *